[ONOS-5839] Performance issue at onos-app-pceweb fix.

Change-Id: Ib3585ea5510491576ec34ebf2b007292479d42bd
diff --git a/apps/pce/pceweb/src/main/java/org/onosproject/pceweb/PceWebTopovMessageHandler.java b/apps/pce/pceweb/src/main/java/org/onosproject/pceweb/PceWebTopovMessageHandler.java
index c1a1bec..f5b1419 100644
--- a/apps/pce/pceweb/src/main/java/org/onosproject/pceweb/PceWebTopovMessageHandler.java
+++ b/apps/pce/pceweb/src/main/java/org/onosproject/pceweb/PceWebTopovMessageHandler.java
@@ -702,13 +702,10 @@
         }
     }
 
-    /**
-     * Handles the event of topology listeners.
-     */
     private void findTunnelAndHighlights() {
         Collection<Tunnel> tunnelSet = null;
         Highlights highlights = new Highlights();
-        paths.removeAll(paths);
+        paths.clear();
         tunnelSet = tunnelService.queryTunnel(MPLS);
         if (tunnelSet.isEmpty()) {
             log.warn("Tunnel does not exist");
@@ -747,12 +744,9 @@
         hilightAndSendPaths(highlights);
     }
 
-    /**
-     * Handles the event of topology listeners.
-     */
     private void highlightsForTunnel(Tunnel tunnel) {
         Highlights highlights = new Highlights();
-        paths.removeAll(paths);
+        paths.clear();
         if (tunnel.path() == null) {
             log.error("path does not exist");
             sendMessage(highlightsMessage(highlights));